Process for making alkaline permanganates, chlorates, and hydrogen.



hing Alkallne Penna nganates,

mas orrica THEODORE J. BREWSTEE, OF NEW YORIL'N. Y.

No Drawing.

To all whom it may concern:

Be it known that I, THEODORE J. Bnnws'rnn, a citizen of the Unit-edStates, residing at New York, in the county of New York and State of NewYork, have invented certain new and useful Improvements in Processes forMali Chlorates, and Hydrogen, of which the following is a specication. o

The object of my invention is to so im prove the present known manner atmaking permanganates of the alkaline metals, and to provide a methodofmaking; them so that commercial use may result of the process.

Alkaline permanganates hr .e previously been made by heating manganeseore with an alkali, sometimes with the addition of an oxidizing agent toincrease the yield, thus forming the mangauate of the metal in question.This manganate would then be ordized to permanganate either by boiling,with Water which causes a precipitation of manganese dioxid, or byoxidation by means of the electric current. Uther means of convertingmanganates to permanganatcs include treatment with chlorin. Thesevarious processes for making the manganates and permanganates are opento the obj ectio r into the chemical l1l(lLl$-" that they do not fittrial conditions Well enough so that a cheap product can be made. I

My invention provides for the utilization of cheap raw materials, andprovides for the return to the process of all products intermediate tothe production of pei'nuinganates and the product-ion of valuableby-prialucts as Well, so that permanganate of potash or soda. may bemade economicall The process starts with muriate of pot-ash, which isavailable in large quantities, or with common salt, in the case that thepermanganate of soda is Wanted; The chlorid of the alkali metal isdissolved in Water and subjected to the action of electricity in theWell known manner, whereby chlorin and the hydroxid of the alkali metalis formed. I then evaporate the product of the electrolytic action Whichconsists of a caustic alkali containing some undecomposed chlorid,

whereby the most of the chlorid separates out from solution and isreturned to the process. The caustic solution, which may be caustic sodaor potash is then mixed with oxide of manganese, preferably Well groundto a fine Specification of Letters Patent.

Patented Jan. 21, 1919.

Application filed Qctober .7, 1917. Serial IZo, 19?,01'7.

powder, and I then heat the mixture until dry.

As the material forms some lumps in this proc ss. I grind the product toas fine a powder as pi sible, then heat it to atemperature best suitedfor the reactitai, which usually above 360 degrees but under a red heat,allowing air to he in contact with the powder, so that oxidation to themanganate an ta he place to the best advantage. Mixing While calciningis heenlieial. I calcine until a sample taken from time to time andanalyzed shears that there is being formed 1U) lllk'li"? llliliillillliiif'.

The L rill-r is then cooled, and leached with. Water. i." solutionconsists of the caustic alkali and maugauate ther with a small amount ofchlorid. "T solution is then treated with an excess of chlorin in such avay that the chloi'in is in excess continually, and the solution ispreferably hot. This manner of treating results in the production oflittle or no hyptuwhlorite, but on the cont ary the it'lllsl'lc alkaliis converted into chlorid and chlorate, and the manganateis convertedinto permanganate.

The re: ctions are practicall quantitative i hlioth cases. For example,one molecule of alkaline manganate reacts with one atom of ,chlorinforming one molecule of alkaline chlorid and one molecule of alkalinepermanganate. In the case of the caustic alkali, siX molecules of thisreact with six atoms of chlorin, forming five molecules of alkalinechlorid and one oif' alkaliue chlorate. hen the chlorination iscomplete, the solution contains-ran alkaline ch orid. chlorate, andpermanganate besides a trace oi ohlorin.

The latter is boiled off or posed of, and the solution is concentratedand the separation into its constituents made by means oii' fractionalcrystallization by Well known methods. The alkaline chlorid returned tothe process, the alkaline chlorate and permanganate are ready for sale.

All of the manganese oxids are not consumed in the calcining operationwith the formation of manganate, but remain after the calcined powderhas been leached with Water. These oxide are returned to the therwisedistain manganese in sutiicient quantity to make the operation pay.

\Vhen oxids of a lower degree of oxidation than the dioxid are used, itusually requires a longer period of calcining to obtain a good result,but otherwise the operation is the same as when the dioxid 1s used.Practically the .whole oithe manganese can be converted intopermanganates,

The electrolysis of the alkaline chlorid produces hydrogen as well asehlorin. This hydrogen can be used for many purposes, such as the h'drogi. nation of oils, ketones, manufacture of ammonia, cfyanamid, etc.It is produced in more or less high purity according to the type ofelectrolytic cell used, and the care in the process. Usually it can behad ninetysve per cent. (95%) pure or better.

The following example shovvs how the processmay be Worked: Ten parts ofmuriate ot' potash is dissolved in thirty parts water, and it themuriate of potash contains any lime, enough carbonate of potash is addedto precipitate the lime as carbonate, and the solution is filtered andted into an electrolytic cell at the best speed suitable for theoperation of the cell. The action of the electrolytic current is todecomposethe n'uiriate of potash into .the alkali metal and ClllOl'lH.In a well constructed cell, it is possible tOTGlI'lOVB the chlorin as itforms ninety (90) to ninety-eight per cent. (98%) pure, and from thecathode, the al- -kali metal unites with Water as soon as formed withthe forn'iation of caustic alkali and hydrogen.

The latter escapes also ninety (-90) to ninety-nine per cent. (Qty/lpine, according t'othe conditions. In this case, caustic potash isformed and is removed in the solution that'flows'from the cell. Thissolution Will contain some undecomposed chlorid, as it is not customaryto operate the cell in a manner that. all of the chlorid is convertedinto caustic. The solution may have the follow ing composition, forexample SlX parts caustic potash, two parts chlorid o1" potash, and

thirty parts water.

This is evaporated until there remains six parts water, whereuponpractlcallyall of the chlorid separates out during the oper ation, andis returned to the process.

. The strong potassium hydroxid solution containing sixparts causticpotash is mixed with nine parts of finely ground oxids of Any lumps arebroken up during the drying, and when the Whole is dry, the product isground as finely as possible in a mill, and then heated'wlnlebemgexposed to the action of air unt11'a,sample Withdrawn from time totime and analyzed shows that no more manganate of potash is being made.

The heating usually of one to four hours is enough, and the temperatureusually chlorate of potash.

for re-use.

'The solution is then treated with chlorin in a manner that there iscontinually an excess of chlorin, thereby avoidingtheformatlon ofhy'pochlorites. The chlorination of the solution results in theformation of permanganate of potash, chlorid of potash, and Any excesschlorin which -may be dissolved in the solution is removed by boiling orother means, and the potash salts are-separated from each other by meansof fractional crystallization, the methods of which are Well known. Thechlorate ofpotash and permanganate are now finished products, While thechlorid of potash is returned to the process.

In some cases it is desirablet o form the permanganate with a minimumamount of chlorate, since the separation of these products presents somediiiiculties. In this case,

the manga'nate solution which contains also a caustic alkali is treatedWithonly the amount of chlorin'necessary tooxidize to the permanganate.This is easily done on'a manufacturing scale by measuring the chlorin bypassing it through a meter into an analyzed solution of the manganate,Where it is absorbed. In this reaction, a portlon o f the chlorin reactsWith the. caustic alkali torming a hypochlorite, While the-balanceoxidizes directly the manganate to' the per-' manganate. If thissolution is then care. fully neutralized with hydrochloric acid, the hy'iochlorite is decomposed With liberation ofchlorin and the unoxidizedmanganate is then converted into permanganate without appreciableamounts of chlorates being formed. The resulting solution will containpractically nothing but the chlorid and permanganate of the alkalimetal, the separation of which is easily performed by.

means of fractional crystallization by known methods. I

There are cases where gin the process with a caustic alkali instead ofan alkaline chlorid, and in this case" it is desirable to recover theexcess caustic alkali To accomplish this result,itis desirable tousecaustic potash insteadof caustic soda, and to prepare the manganatein the manner given. The manganate solution, which contains causticalkali, may be converted into the permanganate form by either of twomethods, the choice of which is made according to local conditions. v v

' The first method consists of diluting the manganate solution to aboutfive (5) to'ten per cent. (10%) strength and boiling, where- Well it isdesirable to'be v answer by the manganate is converted into permanganate according to the following reaction:

' roduct substaniiallv as described.

The manganese dioxid is filtered oh and re turned to the process, andthe permanganate starting the operation is advisable.

solution is evaporated and cryst-allized in the regular manner. Themother liquor of the crystallization contains much caustic alkali and isreturned to the process to be used in place of fresh materials iii-thepreparation of the calcined product.

Thei'seoon'd method of conversion of man-- ganate to permanganateconsists of sub3ectlng'the manganate to the action of the electriccurrent in an electrolytic cell. In this operation practically the Wholeof the man ganate can be converted into permanganate according tothereaction: I

2K MnO +H O+Ux=2KMnO +2l0H.

reducing action is minimized. The addition of a small amount ofpermanganate before The electrolysis may thus beperformedina simple cellwithout the use of a diaphragm. The product of the electrolytic actionconsisting of an alkaline solution of 'p erinanganate is concentratediind' crystallized in the regular way, the rriother' liquor of thecrystallization being returned to the process. Having thus described myinvention, what I claim as new and desire to secure by Letters Patentis:

1. A process of making alkaline manganates conslstmg of mixing oxide ofmariganese with an alkali solution, evaporating name to thisspecification in the to dryness, grindingcalcining. in presence of airor oxygen, and leaching the calcined 2. A process of makingalkalinepermanganates consisiing of mixing OXldS of mananese with asolution containin an alkali '3 7 evaporating: to dryness, grinding,calcining inthe presence or air or oxygen, the product with Water, and.treating the solution with chlorin, substantially as described.

3. A process of making alkaline permanganate-s and chlorates consistingof mixing oxide of manganese with a solutwn contaim ingren alkali,evaporating to dryness, grinding, calcining in the presence of air oroxygen, leaching the product with w ter, and treating the solution withchlorin, substantially as described.

A process oi? making alkaline penned zanates consisting of mixing asolution of a caustic alkali with manganese oxide, evaporating todryness, grinding, calcining in the presence of air or oxygen, leachingthe calcined product; with water, treating the solution with chlorin andhydrochloric acid, substantially as described.

A process of making alkaline perinan '"anates consisting of mixing onidsof inananese with an alkali solution, evaporating o dryness, grinding,calcining in the presnce of air or oxygen, leaching; the calcinedproduct with Water, boiling the Solution, and crystalizing,substantially as described.

6. A process of making alkaline pennanganate consisting of mixing: oxideoi" inanganese "with an alkali solution, evaporating to dryness,grinding, calcining in the presence of air or oxygen, leaching thecalcined product with water, subjecting the resultingsolution toelectrolysis, boiling the solution and crystallizing, substantially asdescribed.

In testimony whereof I have signed my iresence of two subscribingwitnesses.

THEODORE J. BREWSTER.

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